Detectors based on CMOS technology are already known in the prior art. They generally comprise a scintillation layer, made of cesium iodide (CSI) for example, in which incident x-ray radiation is to be converted to low-energy secondary radiation. The secondary radiation then strikes a pixel matrix with individual CMOS measuring pixels disposed below the scintillator, where the signal can be correspondingly measured. A CMOS detector also comprises electronic activation and read-out components and is frequently provided on the pixel matrix itself but can also be provided as additional components, with a first post-processing already being performed, for example an integration over the measuring time and an amplification. It is also conceivable for a CMOS detector to have a component for standardizing recorded x-ray images to a standard brightness. Further influences result due to the modulation transfer function (MTF) of the scintillator.
One disadvantage of CMOS detectors is the possibility of so-called direct hits. Here high-energy x-ray radiation is not converted by the scintillator to secondary radiation but strikes a measuring pixel directly, so that free charges can be generated. These result in a distorted signal response from the pixel, so that a measurement value that clearly deviates upward and therefore image data that clearly deviates upward result. Such interference can be restricted to a single pixel or a single image point of the two-dimensional x-ray image assigned to the pixel, but it is also conceivable for a number of adjacent pixels to be distorted. This produces artifacts, which manifest themselves for example as bright white dots in the final x-ray image.
Correction mechanisms known in the prior art are based mainly on the use of a number of images recorded one after the other in time, it being assumed that the errors only occur in an isolated manner in individual images and therefore it can be concluded from the image data in another x-ray image recorded at a different time whether an artifact is present. A correction method that can be implemented on an individual image is not yet known in the prior art.